Ali on Wiping: If religion was opinion, we would wipe the bottom of shoes

Abdi Khayr reported: Ali ibn Abi Talib, may Allah be pleased with him, said, “If the religion were based upon one’s opinion, one might expect the bottom of the leather sock to be wiped instead of the top, yet I have seen the Messenger of Allah, peace and blessings be upon him, wiping over the upper part of his leather socks.”